Can you check the 'allocation' of a SharePoint list

Not sure how to explain this one.

If I have a SharePoint list of, say, a persons leave requests with the number of days as one of the columns, can I check when a new request comes in that they have allocation left. Example: 10 days taken, leave allowance is 25 therefore a request for 6 days would be allowed but 16 days would be refused.